1. Field of the Invention
The present invention generally relates to an apparatus and method for verifying model-design and a model-design verification program for checking models designed using a 3D-CAD system, and particularly to an apparatus and method for verifying model-design and a model-design verification program for verifying the fits between male-screw models and tapped-hole models that are designed using a 3D-CAD system.
2. Description of the Related Art
As design systems have become more and more complex every year, a method is required in which, in order to eliminate design errors, defects in designing are readily extracted on a 3D-CAD system.
FIG. 18 is a flowchart illustrating a flow of a conventional design using a 3D-CAD system. After designing models on the 3D-CAD system (in the step S101), defects in designed models are extracted by implementing an interference check that is a main function of the 3D-CAD system (in the step S102). Thereafter, the extracted defects are modified (in the step S103). As described above, by modifying defects at a designing stage, design errors can be prevented from leaking into production and the like.
The foregoing interference-check function is provided as a standard feature, in a 3D-CAD system such as the One Space Designer (supplied by CoCreate Software, Inc.), the Pro/ENGINEER (supplied by Parametric Technology Corporation), or the Solid/MX (supplied by Fujitsu Limited).
By implementing interference checks, information can be obtained that suggests that (1) interference occurs between which models, (2) contact occurs between which models, and the like. Based on the information, the CAD user extracts design errors.
FIGS. 19A, 19B, 20A, and 20B are diagrams representing an interference check implemented between models. For example, in the case where an interference check is implemented between a model A 100 and a model B 101 shown in FIG. 19A and both the models interfere with each other, an interference-check result, for example, a table represented in FIG. 19B, is created. Additionally, in the case where, as represented in FIG. 20A, a model C 102 and a model D 103 come into contact with each other, an interference-check result, for example, a table represented in FIG. 20B, is created.
Additionally, Japanese Patent Laid-Open No. 2005-233911 discloses a female-screw inspection jig for detecting a female screw misaligned with respect to the center axis of a prepared hole formed using a drill.
When created in 3-dimensional model, female screws (tapped holes) are often created so as to have a prepared-hole diameter, considering CAM (Computer Aided Manufacturing) coordination and representation by two-dimensional drawing. That is because, in the case where CAM coordination is implemented, information on the drill diameter is required to be handed over to the CAM system and, if the female-screw portion is created so as to have a screw diameter, the diameter is required to be changed from the screw diameter to a prepared-hole diameter (the drill diameter).
Additionally, in the case where a female screw is represented by a two-dimensional drawing, it is known that the screw-diameter portion and the prepared-hole portion are represented by a thin line and a thick line, respectively. For example, a screw-diameter portion 300 and a prepared-hole portion 301 of a female screw illustrated in FIGS. 21A and 21B by two-dimensional drawings are represented by a thin line and a thick line, respectively. In FIG. 21B, a symbol D1 denotes a prepared-hole diameter and a symbol D2 denotes a screw diameter.
In this situation, when a two-dimensional drawing is automatically created from a 3D model, the outline of the 3D model is created by a thick line. Because, if a screw hole is created so as to have a screw diameter, the screw-diameter portion is represented by a thick line, in an automatically created two-dimensional drawing (the prepared-hole line is manually added to the two-dimensional drawing), the line representing the screw-diameter portion is required to be changed from the thick line to a thin line. Accordingly, in the case where female screws (tapped holes) are created in the 3-dimensional model, the female-screw portions are often created so as to have a prepared-hole diameter.
In the case where, in a 3D model, a female-screw portion is created so as to have a prepared-hole diameter, the prepared-hole portion in a two-dimensional drawing is created by means of a thick line. Therefore, it is not necessary to modify the prepared-hole portion. The thin line indicating a screw diameter is required to be manually added to a two-dimensional drawing. However, in the OneSpaceDesigner (a 3D-CAD system supplied by CoCreate Software, Inc.), by creating a female screw so as to have a prepared-hole diameter and providing the screw with a screw attribute (for example, a screw-diameter), a thin line indicating the screw diameter can automatically be added to the female-screw portion in a two-dimensional drawing.
Additionally, in the case of a male-screw model, the screw diameter in a two-dimensional drawing is required to be created by a thick line, and the 3D model is often created so as to have a screw diameter.
In the case where a female screw is created so as to have a prepared-hole diameter and a male screw is created so as to have a screw diameter, an interference check on the 3D model results in an output indicating that interference exists in the portion (a normal portion) between the male-screw model and the female-screw model (tapped-hole model). That is because the male-screw model and the tapped-hole model are created so as to have a screw diameter and a prepared-hole diameter, respectively.
A CAD user implements a check on the 3D model, based on the foregoing interference information. However, it is necessary to check manually whether the interference portion is the portion (normal portion) between the male screw and the tapped hole or a portion (problem portion) between general models, whereby the check work requires a great number of man-hours.
Although a function or a method is conceivable in which an interference check is implemented, with male screws excluded as non-object components. However, in this case, the interference (problem portion) between a male screw and a general model as well as the interference between a male screw and a tapped hole is also excluded, whereby a problem occurs in which some problem portions are not found.